In this lesson I want to take a short detour from Aquinas's Five Ways.
When we argue for God's existence from motion or change ("The universe is in motion, things don't move themselves, there must be an Unmoved Mover at the bottom of it all") or from efficient causality ("Thing come into being, nothing causes itself to come into being, there must be an Uncaused Cause at the bottom of it all") the most common response from an atheist will be to say...
"There is no need. After all, matter and energy are simply eternal and in one form or another the material universe has always existed and has always been in motion."
With this in mind, I want to address this exact idea: Is this true? Does the material universe extend backward through an infinite succession of moments? Does it have no beginning?
An Arabic Argument
The kalam argument gets it's name from an Arabic word which translates literally as "speech" but refers to Arabic philosophy or theology. The argument was popular especially in the late Middle Ages, especially with Arabic philosophers. It seeks to demonstrate that the universe cannot be infinitely old. That there had to be a beginning to it. That the universe is not simply eternal but has a cause.
The argument can be formulated in a couple different ways, but here is the essence of it:
1. Whatever begins to exist has a cause for its coming into being.
2. The universe began to exist.
3. Therefore the universe has a cause for its coming into being.
OK, let's look at this premise by premise.
1. Whatever begins to exist has a cause for its coming into being
Believe me, I understand if most of you reading premise one respond with a furrowed brow and confused "duh." After all, isn't it perfectly self-evident that whatever begins to exist has a cause for it's beginning to exist? Things don't simply come into existence for no reason and with no cause. Isn't this common sense? Yes, it is. Our experience teaches us that rabbits do not pop into existence for no reason. And the vast majority of people you talk to will not challenge the first premise of the argument.
However... there are some who will argue that according to some aspects of quantum mechanics, it "appears" that at the subatomic level events can occur without there being a cause. Entities "seem" to come into existence from nothing and without cause.
A couple of points: First, it's not like there's consensus on this among physicists.
Although based on what we can see at the subatomic level, it "appears" that a photon of light, for instance, might pop into existence from nothing (a "quantum ghost") and for no reason, isn't it most reasonable, many will argue, for us to assume that it does not actually pop into existence without cause and that we simply do not know at this point what the cause of this is? After all, our universal experience outside of this is that nothing occurs without there being a sufficient cause.
Keep in mind that we're talking about something that "seems" to happen, and at a level so infinitesimally small that scientists have barely begun to have the ability to "see" anything at all.
However, if (a) someone is willing to take it as fact that subatomic particles actually do pop into existence from nothing and without cause, and if (b) they are willing to extrapolate from this to the idea that our entire universe has popped into existence from nothing and for no reason, this argument isn't going to convince them.
Of course, for the sake of consistency this critic will also need to accept the fact that trying to explain how the material world works in terms of material causes and effects (i.e. doing science) may be a meaningless pursuit. You know, given that all kinds of things may happen without cause and all kinds of things may come into existence for no reason.
2. The universe began to exist
This second premise of the argument --- that the universe is not infinitely old but began to exist --- has received support in the past century from modern science and Big Bang cosmology.
The Big Bang was first proposed in a scientific paper delivered by Belgian Catholic priest and cosmologist Georges Lemaitre in 1931. It's accepted by nearly all astronomers today. What it says is that the universe began. It began with the explosion of a single particle of infinite density, where all matter and energy were contained in a single mathematical point with no dimensions. This took place some fifteen billion years ago and the resulting universe has been expanding ever since.
Hence there was a moment in which the universe was "created" and came into being.
The second law of thermodynamics supports the idea that the universe had a beginning. How so? Because what it tells us (note that this is a scientific "law" and merely a "theory") is that in any closed system the energy that is available to accomplish work is always decreasing and becoming uniformly distributed. This is a fact. This is what happens.
For example, you put a cup of boiling tea on the counter and over time the tea will cool down and the heat from it will become uniformly distributed throughout the room.
Understanding this, if Hercule Poirot strolls onto the murder scene finds a cup of tea sitting on the counter and still hot, he knows it hasn't been sitting there forever.
Now, what this argues is that the energy in our universe that is available to accomplish work is running down and that the trend is irreversible. It's heading toward a state in which heat will be distributed uniformly and the sun, along with every other source of energy, will have burnt out and grown cold. And (here's the point) the fact that this hasn't already happened proves that the universe is not infinitely old.
As physicist Paul Davies describes it:
If the universe has a finite stock of order, and is changing irreversibly towards disorder --- ultimately to thermodynamic equilibrium --- two very deep inferences follow immediately. The first is that the universe will eventually die, wallowing, as it were, in its own entropy. This is known among physicists as the 'heat death' of the universe. The second is that the universe cannot have existed forever, otherwise it would have reached its equilibrium end state an infinite time ago. Conclusion: the universe did not always exist.
But there are also philosophical arguments that the universe had a beginning and cannot be infinitely old. In fact, it seems that a temporal series of events without beginning (referred to as an "actual infinite") is impossible and cannot exist. I say this for two reasons.
Bonaventure's Puzzle and Hilbert's Hotel
First, when we try to conceive of the material world as extending backward in time forever and ever and ever and ever and ever, we run into certain consequences and conclusions that seem impossible.
St Bonaventure used the following thought experiment: While one revolution of the sun takes place each year, the moon experiences twelve revolutions. It seems then that no matter how far back in time you and I go, counting revolutions, there will always be exactly twelve times as many revolutions for the moon. We can count backward a trillion trillion years and there will always be twelve times as many revolutions for the moon. But... if the past is an infinite series of actual days, then both the sun and the moon have experienced an infinite number of revolutions. Both of them. What?
Wrestling with this problem and wanting to illustrate the difficulty of even conceiving of an actual infinite, in 1924 German mathematician David Hilbert presented his paradox of the Grand Hotel.
It's really pretty funny. Imagine a hotel, he said, with an infinite number of rooms, all of them filled with guests. You'd think the hotel couldn't accommodate anyone else. But suppose a new guest arrives. At first the manager is in a fluster and scratching his head. But then he realizes that by moving the occupant of room one to room two, and the occupant of room two to room three, and so forth to infinity, he can easily accommodate the new visitor by putting him into the now empty room number one.
In fact, by following these same practical steps it turns out the hotel can accommodate an infinite number of new guests arriving on an infinite number of buses and trains -- even though there was already at the start an infinite number of guests occupying its infinite number of rooms.
Now, suppose a guest checks out and leaves. Doesn't matter. It turns out there are still an infinite number of guests staying at the hotel. Suppose every guest in an odd-numbered room checks out and leaves. Half the guests in the hotel leave. And since there are an infinite number of rooms, this means that an infinite number of guests have now left the hotel. Doesn't matter. Mysteriously it turns out that there are still an infinite number of guests remaining at the hotel.
In other words, it seems that you can add one to infinity or subtract one from infinity -- hell, you can add infinity to infinity or subtract infinity from infinity. It makes no difference. However many you add or subtract, you still have infinity. How can this be?
For a good laugh take 60 seconds to watch this little video on Hilbert's Infinite Hotel.
And if you're having a good time with this and want to go even deeper into the craziness, watch this six minute explanation.
So, the very idea of an actual infinite runs us into logical conclusions that seem impossible.
The Impossibility of Traversing an Actual Infinite
But there's more. Let's assume the material world is an actual infinite. Let's assume it really is "beginningless." Let's assume that history really and truly has been an infinite temporal series of events. If this were the case, it seems it would be impossible to cross that actual infinite to reach any point in time whatsoever. Impossible.
Catholic philosopher Peter Kreeft illustrates the problem by thinking about someone attempting to complete an infinite task.
Can an infinite task ever be done or completed? If, in order to reach a certain end, infinitely many steps had to precede it, could the end ever be reached? Of course not ---not even in an infinite time.... In other words, no end would ever be reached.... But what about the step just before the end? Could that point ever be reached? Well, if the task is really infinite, then an infinity of steps must also have preceded it. And therefore the step just before the end could also never be reached. But then neither could the step just before that one have been reached. In fact, no step in the sequence could be reached, because an infinity of steps must always have preceded any step...
For example, it's impossible to count to infinity. Start counting --- one, two, three, four. No matter how high you count you can always add one to the number you have in your head. You could count a million years, or a billion, or a trillion trillion, and the total would always be some finite number you could specify. "So far I've reached..."
It's impossible to reach infinity counting one at a time.
But then (here's the inescapable problem) if the past amounts to an infinite series of moments that occurred one at a time, the present moment in which you are reading this sentence could not be reached. It would be impossible to ever get to "now." Therefore, either we must conclude that this present moment has not been reached or that there has not been an infinite number of moments preceding this present moment. But since it's perfectly obvious that this present moment has been reached, there cannot have been an infinite number of moments preceding it.
In other words, it is impossible for the material world to be an actual infinite without beginning. The universe had a beginning. At some point it began to exist.
And since whatever comes to exist has a cause for its coming into being...
3. Therefore the universe has a cause for its coming into being.
It hasn't simply "always existed." It was "caused" to be.